Drawing-compasses.



No. 774,327. PATENTBD NOV. 8, 1904.

D. W. MACDONALD.

DRAWING GOMPASSBS.

APPLICATION FILED MAY 11, 1903.

UNITED STATES Patented November 8, 1904.

PATENT OFFICE.

DRAWlNG-COMPASSES.

SPECIFICATIdN forming part of Letters Patent N0. 774,327, dated November 8, 1904.

Application filed May 11, 1903.

To aZZ whom it may concern:

Be it known that I, DUNCAN WILLIAM MAC- DONALD, of Havelock North,-in the Provincial District of Hawkes Bay, in the Colony of New Zealand, do hereby declare the nature of my invention for Improvements in Drawing-Compasses, and in what manner the same is to be performed, to be particularly described andascertained in and by the following statement.

This invention relates to compasses used for geometrical,machine, and mathematical drawing; and my object is to provide-means whereby the legs may be fixed at any distance apart, the distance being indicated in lineal measurement.

The invention is applicable to what are known as dividers and to pencil or pen compasses and the like.

To the inside of one leg I pivotally attach an arm, the opposite end of which is bent approximately at right angles and receives the opposite leg of the instrument. Upon this leg is marked by stamping or engraving in the usual way a scale in inches and fractions thereof, and the widths between the points of the legs of the compass are indicated by the position of the end of the arm upon the scale.

The arm may entirely surround the leg and be provided with a set-screw, by means of which it may be clasped upon the leg and the width of opening of the compass thereby fixed. The arm may be grooved upon the sides facing either leg to receive the leg when the compass is closed.

The drawings herewith illustrate the invention, Figure 1 being a side view of a pair of compasses closed and fitted with my invention; Fig. 2, a similar view with the compasses open; Fig. 3, a cross-section of the pivoted arm on line A A, Fig. 2. Fig. 4: shows'a modification.

The arm 1 is pivoted by a pin 2 to the leg 3 of the compass, the end of the said arm be- Serial No. 156,596. (No model.)

ing bent to form a socket, as shown, to receive the leg 5, which is provided with a scale 6. The arm is locked to the leg 5 by a setscrew 7 A groove 10, Fig. 3, is formed in the arm for receiving the leg 3 when the compasses are closed.

In-the modification shown by Fig. i the socket 4: is pivoted by a pin 9 to the arm 1.

To use instrument, thescrew 7 is unscrewed to set free the leg 5, and upon the compasses being opened the said leg slides through the socket 4 of the arm, the distance apart of the points of the legs being shown by the position of the said socket upon the scale.

What I claim by my invention, and desire to secure by Letters Patent, isr 1. In adrawing-compass for the purpose indicated in combination, a leg 3, the arm 1, pivoted thereon, a leg 5, the socket 4:, upon the end of said arm-receiving leg 5, and the set-screw 7, a scale being marked upon leg 5, upon which by means of the socket 4:, the distance apart of the points of the instrument-is indicated, as specified.

2. In a drawing-compass for the purpose indicated in combination legs pivoted together at their upper ends, an arm pivoted upon one of said legs at one of its ends and having a socket at its other end receiving the other leg, a recess in the upper edge of the arm to receive a leg when the instrument is closed, the leg which passes through said socket having markings upon it by which the distance apart of the points of the instrument is indicated as specified.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

Dated this 7th day of April, 1903.

DUNCAN WILLIAM MACDONALD.

Witnesses:

(J. D. CORNFORD, J. F. MORLEY. 

